The purpose of this NCRR Shared Instrument Grant application is to secure funding to purchase an LSRII polychromatic analytical flow cytometer for the Flow Cytometry Core Facility (FCCF) at the University of Virginia School of Medicine. The FCCF is a very heavily used core facility at the University of Virginia and provides flow cytometry related services on a fee for service basis to the University community in general and particularly to NIH funded investigators in the School of Medicine. The FCCF currently serves over 200 investigators from the laboratories of 98 PIs from 27 different departments. Twenty seven of these PIs use the FCCF for polychromatic (>5 color) flow cytometry (PFC) experiments. The FCCF has a single Cyan ADP nine color instrument, which is currently run at >78% capacity and is the only analytical flow cytometer capable of more than 6 colors and a violet laser within 100 miles of UVA. The use of PFC has steadily increased since 2004 and has exploded over the past year. Increased use of PFC is the result of educational programs instituted by the FCCF that have greatly increased the awareness as well as the current trend in many scientific fields as evidenced in the literature. In addition, many other academic institutions with which our investigators have active collaborations have access to instrumentation capable of more than five colors. The lack of backup instrumentation and the technical limitation of only nine colors have prevented the FCCF from expanding to meet the needs of the UVA research community. Purchase and implementation of the LSRII will 1) allow the FCCF to meet current demand for PFC, 2) meet anticipated requirements for increased capacity in the near future, 3) provide back up capability when the current machine needs repairs and 4) increase services available to the UVA research community by increasing the number of parameters available for analysis. Public Health Relevance: PFC is a technique of fundamental importance in current biomedical research, crosses many disciplines and is used by individuals doing basic, clinical and translational research working on problems related to cancer, infectious disease, aging, immunology, neuroscience and cardiovascular disease among many others. The increased demand for PFC services at UVA has greatly outstripped the capacity and capability of existing instrumentation and has become a serious bottleneck to completing a wide variety of research projects funded in a large part by the NIH. Purchase of an LSRII will relieve this bottleneck and extend our capabilities.